From 3d11275505694ce4e5256516de1c5dd90e749303 Mon Sep 17 00:00:00 2001 From: Garima Singh Date: Mon, 30 Mar 2020 00:31:30 +0000 Subject: [PATCH] commit-graph: examine commits by generation number When running 'git commit-graph write --changed-paths', we sort the commits by pack-order to save time when computing the changed-paths bloom filters. This does not help when finding the commits via the '--reachable' flag. If not using pack-order, then sort by generation number before examining the diff. Commits with similar generation are more likely to have many trees in common, making the diff faster. On the Linux kernel repository, this change reduced the computation time for 'git commit-graph write --reachable --changed-paths' from 3m00s to 1m37s. Helped-by: Jeff King Signed-off-by: Derrick Stolee Signed-off-by: Garima Singh Signed-off-by: Junio C Hamano --- commit-graph.c | 33 ++++++++++++++++++++++++++++++--- 1 file changed, 30 insertions(+), 3 deletions(-) diff --git a/commit-graph.c b/commit-graph.c index 31b06f878c..732c81fa1b 100644 --- a/commit-graph.c +++ b/commit-graph.c @@ -70,6 +70,25 @@ static int commit_pos_cmp(const void *va, const void *vb) commit_pos_at(&commit_pos, b); } +static int commit_gen_cmp(const void *va, const void *vb) +{ + const struct commit *a = *(const struct commit **)va; + const struct commit *b = *(const struct commit **)vb; + + /* lower generation commits first */ + if (a->generation < b->generation) + return -1; + else if (a->generation > b->generation) + return 1; + + /* use date as a heuristic when generations are equal */ + if (a->date < b->date) + return -1; + else if (a->date > b->date) + return 1; + return 0; +} + char *get_commit_graph_filename(struct object_directory *obj_dir) { return xstrfmt("%s/info/commit-graph", obj_dir->path); @@ -815,7 +834,8 @@ struct write_commit_graph_context { report_progress:1, split:1, check_oids:1, - changed_paths:1; + changed_paths:1, + order_by_pack:1; const struct split_commit_graph_opts *split_opts; size_t total_bloom_filter_data_size; @@ -1178,7 +1198,11 @@ static void compute_bloom_filters(struct write_commit_graph_context *ctx) ALLOC_ARRAY(sorted_commits, ctx->commits.nr); COPY_ARRAY(sorted_commits, ctx->commits.list, ctx->commits.nr); - QSORT(sorted_commits, ctx->commits.nr, commit_pos_cmp); + + if (ctx->order_by_pack) + QSORT(sorted_commits, ctx->commits.nr, commit_pos_cmp); + else + QSORT(sorted_commits, ctx->commits.nr, commit_gen_cmp); for (i = 0; i < ctx->commits.nr; i++) { struct commit *c = sorted_commits[i]; @@ -1884,6 +1908,7 @@ int write_commit_graph(struct object_directory *odb, } if (pack_indexes) { + ctx->order_by_pack = 1; if ((res = fill_oids_from_packs(ctx, pack_indexes))) goto cleanup; } @@ -1893,8 +1918,10 @@ int write_commit_graph(struct object_directory *odb, goto cleanup; } - if (!pack_indexes && !commit_hex) + if (!pack_indexes && !commit_hex) { + ctx->order_by_pack = 1; fill_oids_from_all_packs(ctx); + } close_reachable(ctx);